In general terms, an oil well pumping system begins with an above-ground pumping unit, which creates the up and down pumping action that moves the oil (or other substance being pumped) out of the ground and into a flow line, from which the oil is taken to a storage tank or other such structure.
Below ground, a shaft is lined with piping known as “tubing.” A sucker rod, which is ultimately, indirectly coupled at its north end to the above-ground pumping unit is inserted into the tubing. The sucker rod is coupled at its south end indirectly to the subsurface oil pump itself, which is also located within the tubing, which is sealed at its base to the tubing. The sucker rod couples to the oil pump at a coupling known as a 3-wing cage. The subsurface oil pump has a number of basic components, including a barrel and a plunger. The plunger operates within the barrel, and the barrel, in turn, is positioned within the tubing.
Beginning at the south end, subsurface oil pumps generally include a standing valve, which has a ball therein, the purpose of which is to regulate the passage of oil (or other substance being pumped) from downhole into the pump, allowing the pumped matter to be moved northward out of the system and into the flow line, while preventing the pumped matter from dropping back southward into the hole. Oil is permitted to pass through the standing valve and into the pump by the movement of the ball off of its seat, and oil is prevented from dropping back into the hole by the seating of the ball.
North of the standing valve, coupled to the sucker rod, is a traveling valve. The purpose of a conventional traveling valve is to regulate the passage of oil from within the pump northward in the direction of the flow line, while preventing the pumped oil from slipping back down in the direction of the standing valve and hole.
In use, oil is pumped from a hole through a series of “downstrokes” and “upstrokes” of the oil pump, wherein these motions are imparted by the above-ground pumping unit. During the upstroke, formation pressure causes the ball in the standing valve to move upward, allowing the oil to pass through the standing valve and into the barrel of the oil pump. This oil will be held in place between the standing valve and the traveling valve. In the conventional traveling valve, the ball is located in the seated position. It is held there by the pressure from the oil that has been previously pumped. The oil located above the traveling valve is moved northward in the direction of the 3-wing cage at the end of the oil pump.
During the downstroke, the ball in the conventional traveling valve unseats, permitting the oil that has passed through the standing valve to pass therethrough. Also during the downstroke, the ball in the standing valve seats, preventing the pumped oil from slipping back down into the hole.
The process repeats itself again and again, with oil essentially being moved in stages from the hole, to above the standing valve and in the oil pump, to above the traveling valve and out of the oil pump. As the oil pump fills, the oil passes through the 3-wing cage and into the tubing. As the tubing is filled, the oil passes into the flow line, from which the oil is taken to a storage tank or other such structure.
Fluid that is pumped from the ground is generally impure, and includes solid impurities such as sand, pebbles, limestone, and other sediment and debris. Certain kinds of pumped fluids, such as heavy crude, tend to contain a relatively large amount of solids.
Solid impurities may be harmful to a pumping apparatus and its components for a number of reasons. For example, sand can become trapped between pump components, causing damage, reducing effectiveness, and sometimes requiring a halt to pumping operations and replacement of the damaged component(s). This can be both time consuming and expensive.
The present invention addresses these problems encountered in prior art pumping systems and provides other, related, advantages.